1. Field of the Invention
The present invention relates to a device for providing a visual display of a condition of air flow to or from a ventilated rack of animal cages.
2. Description of the Related Art
Systems for providing air and removing exhaust from racks containing animal cages are known. U.S. Pat. No. 5,307,757 describes a ventilated animal rack and animal cage system including a forced air system in which positive air is supplied by an air inlet manifold. Air is removed from the cage by negative air pressure to an exhaust manifold. The exhausted air is treated with a laboratory air treatment system or portable HEPA filtered exhaust unit and is released to the atmosphere.
Alternatively, exhaust for a rack of animal cages is removed by a central exhaust system. Several racks can be connected to the exhaust system. One end of an exhaust drop is connected to a duct of the exhaust system for removing exhaust. The other end of the drop is connected to an exhaust plenum of the rack of animal cages. The exhaust operates by negative pressure. Air is supplied to the ventilated rack by a central system or with a rack mounted supply blower. A conventional damper has been used to permit air flow to or from the rack to be adjusted and measured at one location. The damper is attached to a drop of either the exhaust system or the air flow system. An example of a conventional damper is manufactured by Continental Fan Manufacturing as an Iris Damper SP1-100. Interlocking steel plates and a calibrated control lever form an adjustable aperture. A pair of pressure ports extend from either side of the aperture of the damper. By measuring differential pressure across the pressure ports and referring to a graph of a matching performance curve, an air flow rate can be determined. Thereafter, the damper can be adjusted to adjust the air flow rate.
It is desirable to provide a device for automatically providing a visual verification of proper air flow to or from a ventilated rack of animal cages, thereby assisting in assessing a barrier condition of the ventilated rack.
The present invention relates to a device for displaying a condition of air flow to or from a ventilated rack of animal cages in which a damper is coupled between the ventilated rack and an air inlet or exhaust outlet. Air pressure is measured within the damper. A condition of the measured pressure is visually displayed. The display can include a plurality of color coded portions for indicating that the condition is within or outside of a preferred operating range, thereby providing a visual assurance that the ventilated rack of animal cages is maintaining a barrier condition. In addition, the display can indicate a value of the measured pressure or a flow rate. When the display indicates that the condition of the air flow is outside of the preferred operating range, the damper can be manually or automatically adjusted to enable the preferred operating range to be obtained. A barrier condition of the rack is obtained when the preferred operating range is maintained